Today, new types of circuit-switched communication networks are being developed for the transfer of information using synchronous time division multiplexed bitstreams. Within this field, a new technology, referred DTM (Dynamic synchronous Transfer Mode), are currently being developed, primarily addressing the problem of providing quality of service to users of real-time, broadband applications.
The structure of a DTM network has been described in, e.g., “The DTM Gigabit Network”, Christer Bohm, Per Lindgren, Lars Ramfelt, and Peter Sjödin, Journal of High Speed Networks, 3(2):109–126, 1994, and in “Multi-gigabit networking based on DTM”, Lars Gauffin, Lars Häkansson, and Björn Pehrson, Computer networks and ISDN Systems, 24(2):119–139, April 1992.
The basic topology of a DTM network is preferably a bus with two unidirectional, multi-access, multi-channel optical fibers connecting a number of nodes, each node being arranged to serve one or more end users connected thereto. However, the topology may just as well be any other kind of structures e.g. a ring structure or a hub structure.
When transferring asynchronous traffic, such as TCP/IP packets or Ethernet frames, a mechanism for providing routing of such traffic through, e.g., a DTM network is needed. This is typically solved by the provision of routing apparatuses at different locations in the network.
Typically, such a routing apparatus comprises one or more interfaces providing access to respective multi-channel bitstreams carrying isochronous channels, a routing processor for providing routing of data packets, and a communication bus interconnecting said interfaces and said routing processor.
A problem in this type of routing apparatus is that the capacity demand placed upon on the routing processor, as well as the transfer capacity demand placed upon the communication bus, becomes high as several interfaces needs access to the function provided by the one routing processor. When these demands exceed the available capacity, blocking will occur, resulting in delays or even loss of data.
An object of the invention is therefore to provide a routing apparatus designed to reduce the risk of lack of capacity, thereby limiting the occurrence of blocking or loss of data in relation to the routing processor.